Get the underwater shape, simply cropping the provided shape by the z=0
free surface plane.
Position arguments:
shape -- Solid shape to be cropped
Keyword arguments:
force -- True if in case the common boolean operation fails, i.e. returns
no solids, the tool should retry it slightly moving the free surface. False
otherwise. (True by default)
Returned value:
Cropped shape. It is not modifying the input shape

Compute the moment required to trim the ship 1cm
Position arguments:
ship -- Ship object (see createShip)
Keyword arguments:
draft -- Ship draft (Design ship draft by default)
roll -- Roll angle (0 degrees by default)
trim -- Trim angle (0 degrees by default)
Returned value:
Moment required to trim the ship 1cm. Such moment is positive if it cause a
positive trim angle. The moment is expressed as a mass by a distance, not as
a force by a distance

Move the ship shape such that the free surface matches with the plane
z=0. The transformation will be applied on the input shape, so copy it
before calling this method if it should be preserved.
Position arguments:
shape -- Ship shape
draft -- Ship draft
roll -- Roll angle
trim -- Trim angle
Returned values:
shape -- The same transformed input shape. Just for debugging purposes, you
can discard it.
base_z -- The new base z coordinate (after applying the roll angle). Useful
if you want to revert back the transformation